In recent years, in a condensing process of a refrigerant in a refrigeration cycle for a car air-conditioning system or the like, a technique for subcooling a condensed refrigerant to a temperature lower than the condensing temperature by several degrees is proposed. In this technique, the refrigerant whose heat releasing amount was increased by the subcooling is introduced to a decompressing means and an evaporator so as to increase the heat absorption amount at the time of the refrigerant evaporation, to thereby improve the refrigeration capacity.
In performing this proposed technique, a heat exchanger with a receiver-tank (subcool system condenser) in which a receiver-tank is attached to a heat exchanger integrally provided with a condensing portion and a subcooling portion is now under development.
As shown in FIG. 8, in this heat exchanger with a receiver-tank, a heat exchanger main body 100 includes a pair of headers 101 and 101 and a plurality of heat exchanging tubes 100 disposed in parallel with their opposite ends communicated with the headers. The heat exchanging tubes are classified into a plurality of passes P1 to P5 by partitions 102 provided in the headers 101. The passes P1-P3 constitute a condensing portion 110, and the passes P4 and P5 constitute a subcooling portion 120 independent to the condensing portion 110.
A condensing portion inlet 111 and a condensing portion outlet 112 are provided at the upper and lower portions of the condensing portion 110 of the header 101, respectively. A subcooling portion inlet 121 and a subcooling portion outlet 122 are provided at the upper and lower portions of the subcooling portion 120 of the header 101, respectively.
A receiver-tank 130 attached to the header 101 is provided with a receiver-tank inlet 131 communicated with the condensing portion outlet 112 and a receiver tank outlet 132 communicated with the subcooling portion inlet 121.
In this heat exchanger with a receiver-tank, the gaseous refrigerant flowed into the condensing portion 110 from the condensing portion inlet 111 is condensed by exchanging heat between the refrigerant and the ambient air while passing through each of the passes P1 to P3 of the condensing portion 110. The condensed refrigerant is introduced into the receiver-tank 130 via the condensing portion outlet 112 and the receiver-tank inlet 131, and once stored in the receiver-tank. Then, only the liquefied refrigerant is introduced into the subcooling portion 120 via the receiver tank outlet 132 and the subcooling portion inlet 121. Furthermore, the liquefied refrigerant flowed into the subcooling portion 120 is subcooled by the ambient air while passing through the fourth and fifth passes P4 and P5, and then flows out of the subcooling portion outlet 122.
In the heat exchanger integrally provided with such a receiver-tank, for example, as shown in FIG. 9, the receiver-tank 130 is connected to the heat exchanger main body 100 via a joint member such as a block flange 140.
This flange 140 is integrally provided with a first block 151 joined to the condensing portion outlet 112 or the vicinity thereof of one of the headers 101 of the heat exchanger main body 100 and a second block 152 joined to the subcooling portion inlet 131 or the vicinity thereof. The first block 151 is provided with an inlet flow passage 141 having one end (outlet side end portion) opened to the flange upper surface and the other end (inlet side end portion) communicating with the condensing portion outlet 112. The second block 152 is provided with an outlet flow passage 142 having one end (inlet side end portion) opened to the flange upper surface and the other end (outlet side end portion) communicating with the subcooling portion inlet 121.
On the other hand, the receiver-tank 130 is provided with a lower end closing member 136 having a receiver-tank inlet 131 and a receiver tank outlet 132 each communicating with the inside of the tank.
The receiver-tank inlet and outlet 131 and 131 are joined to and communicated with the end portions of the inlet flow passage 141 and the outlet flow passage 142 of the block flange 140 via joint pipes 145 and 145, respectively. In this joined state, the receiver-tank 140 is attached to the upper surface of the block flange 140.
In the refrigeration system for a car air-conditioner to which the aforementioned heat exchanger with a receiver-tank is applied, it is required to be small in size and light in weight in order to effectively use the limited space in a car body.
However, when making the receiver-tank 130 smaller, the tank volume becomes smaller, and therefore the stable range of the refrigerant, i.e., the stable range in the subcooling state of the refrigerant with respect to the amount of sealed refrigerant becomes narrower. This tends to cause an excessive or shortage of sealed amount of refrigerant, resulting in unstable refrigeration performance.
Furthermore, when making the heat exchanger main body 100 smaller, the core area for refrigerant condensation becomes smaller. This makes it difficult to stably supply a liquefied refrigerant, resulting in poor refrigeration performance.
On the other hand, in the condensing apparatus such as the aforementioned heat exchanger with a receiver-tank or a refrigeration system, it is actually required to decrease the number of parts, improve the workability and decrease the costs besides the aforementioned miniaturization.
It is an object of the present invention to solve the problems of the aforementioned prior art, provide a condensing apparatus such as a heat exchanger with a receiver-tank etc. capable of miniaturizing, obtaining stable refrigeration performance, decreasing the number of parts and the costs and improving assembling workability, and to provide a refrigeration system.